generating the body of the finally clause _four_ times is one time too many

#KT-1688 Fixed

compiler/testData/codegen/regressions/kt1688.kt

@@ -0,0 +1,10 @@
+fun box(): String {
+    var s = ""
+    try {
+        throw RuntimeException()
+    } catch (e : RuntimeException) {
+    } finally {
+        s += "OK"
+    }
+    return s
+}